Banded ceramic valve and/or port plate

ABSTRACT

Valve and/or port plates incorporating or formed entirely of ceramic can each be provided with a reinforcing band. The band, which can optionally be metal, can be placed around the plate to provide additional strength to the plate, thereby allowing for a reduction in the overall diameter and/or thickness of the plates and, thus, the use of less ceramic material. The band can hold the plate in compression and/or be glued to hold the band in place.

FIELD

Valve and port plates having, such as those suitable for use in rotaryaxial piston pumps or pressure exchangers, are described herein and, inparticular valve and port plates having ceramic interface surfaces.

BACKGROUND

Rotary axial piston pumps (RAPPs) are known in the art and can beconstructed for a number of different end-use applications. One categoryof RAPPs are configured for use in applications, e.g., oil hydraulictransport, that permit the internal components that are subjected tofriction to be oil lubricated, thereby helping to reduce the unwantedeffects of friction to provide a desired service life. Another categoryof RAPPs are configured for use in applications, e.g., water hydraulictransport, that do not permit the internal components subjection tofriction to be oil lubricated. In such applications, the RAPPs areconfigured to use plain water without additives or aides as the onlyfriction lubricating medium.

Conventional RAPPs configured for water hydraulic transport service useinternal parts, subjected to friction during use, that are specificallyconfigured to include a polymeric low-friction surface feature. Such aconventional RAPPs comprise metallic valve and port plates that includea polymeric interface surfaces.

While such RAPPs are configured to address frictional wear effectsbetween adjacent metallic parts during water hydraulic transport use,the use of such RAPPs configured in the manner described require thatthe water entering the pump be filtered to very high levels to removeparticulate matter. If unfiltered to a sufficient degree, theparticulate matter in the water can otherwise wear and/or damagepolymeric surface feature resulting in metal-to-metal contact, therebyreducing the effective service life of the RAPP. The need to filter thewater transported by the RAPPs to protect against unwanted damage and/orreduced service life involves using filtration equipment that adds laborand material costs to the overall cost of operating such RAPPs.Furthermore, wear can adversely impact the precision clearances reliedupon for sealing, and can thereby result in loss in pump efficiency andflow.

Thus, while RAPPs configured for water transport service are constructedto provide some degree of low friction operation under certain operatingconditions, e.g., ultra-clean conditions, it is desired that an RAPP beconstructed in a manner that permits a more robust operating parametersin water transport services in terms of both improved service life andin terms of reduced water pretreatment requirements. Specifically, it isdesired that an RAPP be constructed in a manner comprising internalparts specially developed and engineered to provide an improved degreeof friction reduction performance, thereby extending service life whencompared to conventional water transport RAPPs.

It is further desired that such RAPPs comprising such constructionprovide the improved degree of friction reduction performance in amanner that avoids the need to filter the incoming water to ultra-finestandards, thereby reducing the overall equipment and labor costsassociated with RAPP operation. Finally, it is desired that such RAPP beconstructed in a manner avoiding the use of exotic materials and/ornonconventional manufacturing techniques, thereby minimizing any suchimpact on material and manufacturing costs.

One solution to the aforementioned problem is to use ceramic valve andport plates. Ceramic valve and port plates can advantageously reducewear and erosion while being manufactured with the precise tolerances,and can be particularly suitable for use in water-lubricated pumps. Theceramic valve and port plates can be used in RAPPs as well as pressureexchangers, for example. However, ceramic can be expensive as comparedto metal components, and can fracture.

SUMMARY

In order to improve the resistance to fracturing as well as reduce thecosts associated with the use of ceramic materials, valve and/or portplates can each be provided with a reinforcing band. The band, which canoptionally be metal, can be placed around the plate. The band serves twopurposes. One is provide additional strength to the plate, therebyallowing for a reduction in the overall diameter and/or thickness of theplates. The end result is that less ceramic material can translate intoa cost savings. The other is to hold the plate together in case of afailure, such as a crack. This can eliminate or at least reduce thespread of debris throughout the pump. The band can hold the plate incompression. This can be accomplished by applying a heated band around arelatively cool ceramic plate, then allowing the heated band to cool andcontract to place the ceramic plate in compression. Alternatively, theband could be glued to the ceramic plate.

The banded ceramic valve and/or port plates described herein can beincorporated into RAPPs, pressure exchangers or other suitable devices.An exemplary RAPP, such as that disclosed in U.S. Publ. Appl. No.2013/0118346, which is hereby incorporated by reference in its entirety,can comprise a housing, a swash plate that includes an inclined surface,and a rotor assembly that is positioned adjacent the swash plate. Therotor assembly comprises a rotor-drum that has at least one cylinderbore disposed therein, and that has piston(s) disposed within therespective cylinder bore(s). The pistons are constructed having aball-shaped end that extends from the cylinder bore(s). At least oneslipper is interposed between the swash plate and the rotor-drum. Theslipper(s) comprises socket joints for accommodating the pistonball-shaped end(s) therein. The port plate is positioned adjacent an endblock that is disposed in the housing open end, and the valve plate thatis interposed between the port plate and the rotor-drum. In an exemplaryembodiment, the port plate comprises an interface surface that is incontact with the valve plate, and that is formed from ceramic material.In another exemplary embodiment, the valve plate comprises an interfacesurface that is in contact with the port plate, and that is formed froma ceramic material. In yet another exemplary embodiment, both the valveand port plates have ceramic interface surfaces. In another exemplaryembodiment, the port plate and/or the valve plate may be formed entirelyfrom a ceramic material. Unlike the RAPP in the aforementionedpublication, either or both of the plates can have the aforementionedreinforcing band. The band can either be disposed about the outercircumference of the plate, disposed radially inward relative to theouter circumference of the plate or more than one band can be providedwith one band in each position.

In one aspect, a set of valve and port plates configured for use in arotary axial piston pump or pressure exchanger are provided, whereineach of the plates includes a ceramic interface surface for rotatablysliding engagement with the other plate. A reinforcing band radiallysurrounds one of the ceramic interface surfaces to hold the surface incompression, which can be either the ceramic interface surface of thevalve plate or the port plate. Each plate can have its own reinforcingband to hold its ceramic interface surface in compression. Each of theplates ca be ceramic and the reinforcing bands can surround the outercircumference of the plates or a radially inward portion thereof.

In another aspect, the plate or plates having the reinforcing band orbands can be incorporated into a RAPP, a pressure exchanger, or otherdevice. In an exemplary aspect, the RAPP can include a housing, a swashplate having an inclined surface, and a rotor assembly positionedadjacent the swash plate. The rotor assembly can include a rotor-drumhaving at least one cylinder bore disposed therein, and having piston(s)disposed within the respective cylinder bore(s), wherein the pistonshaving a ball-shaped end extending from the cylinder bore(s). At leastone slipper can be interposed between the swash plate and therotor-drum. The slipper can have socket joints for accommodating thepiston ball-shaped end(s) therein and a swash plate interface surface incontact with the swash plate inclined surface which swash plateinterface can optionally be formed from a ceramic material. A port plateis positioned adjacent an end block disposed in the housing open end,and a valve plate interposed between the port plate and the rotor-drum.The port and valve plates each have a ceramic surface at an interfacethereof. A reinforcing band is provided surrounding at least a portion,such as the outer circumference or a radially inward portion, of one ofthe plates, either the valve or port plate, to hold the plate incompression. A second such reinforcing band can be provided about atleast a portion of the other of the plates. The band can optionally beformed of a metal.

In one aspect, the reinforcing band is disposed about the outercircumference of the one of the plates. In another aspect, thereinforcing band is disposed radially inward relative to an outercircumference of the plate. In yet another aspect, the reinforcing bandis provided with one or more recessed pockets. Either or both of theplates can be formed of a ceramic material, as opposed to just theinterface surfaces. Indeed, both plates can be ceramic and each can havetheir own reinforcing band.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of a RAPP where the RAPPincorporates a ceramic valve plate and a ceramic port plate, each with ametal reinforcing band;

FIG. 2 is a front perspective view of a valve and port plate set havinga band disposed about the circumference of each plate;

FIG. 3 is a side elevation view of the valve and port plate set of FIG.2;

FIG. 4 is a rear perspective view of the valve and port plate assemblyof FIG. 2;

FIG. 5 is a front elevation view of the valve plate of FIG. 2 showingthe interface surface;

FIG. 6 is a rear elevation view of the port plate of FIG. 2 showing theinterface surface;

FIG. 7 is a side elevation view of a first alternative band for use withthe valve and port plates of FIG. 2, where the band has a pair of rimsor flanges and a recess therebetween; and

FIG. 8 is a side elevation view of a second alternative band for usewith the valve and port plates of FIG. 2, wherein the band has a singlerim or flange with a recess to the side thereof.

DETAILED DESCRIPTION

In order to improve the resistance to fracturing as well as reduce thecosts associated with the use of ceramic materials, valve and/or portplates can each be provided with a reinforcing band. The valve and/orport plates can be incorporated into a RAPP, pressure exchanger or otherdevice. Although FIG. 1 depicts reinforced ceramic valve and port platesincorporated into a RAPP, it will be understood that such reinforcedceramic valve and port plates could alternatively be incorporated intonumerous other machine designs, such as pressure exchangers and othervalve systems.

The valve plate 10 and port plate 20 can be provided as part of a set,as shown in FIGS. 2-4, and each plate can have an outer surroundingmetal band 12 or 22 disposed about the outer circumference of the plateor, alternatively or in addition, a radially inward metal bend. Thevalve plate 10 and port plate 20 can each be made entirely of ceramicor, at a minimum, have ceramic material disposed where the two plates 10and 20 slide against each other when rotating relative to each other.The bands 12 and 22 can function to provide additional strength to therespective plates 10 and 20. This in turn can lead to reduced thicknessand/or reduced diameter plates 10 and 20, which in turn can lead to lessceramic material, which in turn can lead to reduced cost plates.Furthermore, the use of the reinforcing bands 12 and 22 can eliminate orat least reduce fractures to the plates 10 and 20 from resulting infragments becoming distributed elsewhere throughout the machinery.

Turning now to details regarding the bands 12 and 22, they can be madeof a metal, such as aluminum, stainless steel, carbon steel, or thelike. The metal can be formed from a strip of material which is shapedinto a hoop and then lap welded or, alternatively formed into a hoop bycutting using a lathe from stock metal pipe. The metal bands can have athickness suitable for the application. In the example of a RAPP, thethickness can be between about 0.12 inches and about 0.50 inches. Themetal bands can alternatively have a thickness than varies, such as byhaving one or more rims or flanges. For example, a first alternativeband 110 for use with the valve and port plates is depicted in FIG. 7,where the band 110 has a pair of rims or flanges 112 projecting radiallyfrom the edges in order to form a recess or pocket 114 therebetween. Asecond alternative band 212 for use with the valve and port plates isdepicted in FIG. 8, wherein the band 212 has a single rim or flange 112projecting radially from an edge of the band with a recess or pocket 114to the side thereof.

The plates 10 and 20 do not have to be specially modified to accommodatethe bands 12 and 22, such as if they are made of a ceramic material. Insuch a case, and as illustrated in FIGS. 2-4, the metal bands 12 and 22can be disposed about the outer circumference of each of the respectiveplates 10 and 20. They can be held in place using friction and,preferably though not necessarily, hold the plates 10 and 20 incompression. Such a friction and compression fit can be accomplished,for example, by heating the bands 12 and 22 so that they enlarge and canslip around the outer circumference of the respective plate 10 and 20.The plates 10 and 20 can optionally be cooled as well. Once the bands 12and 22 contract, the friction fit and compression forces can result.Alternatively or in addition, glue can be used to hold the bands 12 and22 in place. A hydraulic press can be used to slip the bands 12 and 22around the outer circumference of the plates 10 and 20. While the plates10 and 20 do not have to be specially modified to accommodate the bands12 and 22, they could be so modified. For example, a groove could beformed to at least partially seat the bands, or protuberances could beformed that mate with apertures or recesses of the band.

Each of the plates 10 and 20 has an interface surface, shown in FIGS. 5and 6, where they slidingly engage when rotated relative to each otherduring operation. While the entire plates 10 and 20 can be formed ofceramic, as an alternative at least those interface surfaces can beformed of ceramic material. Examples of suitable ceramic materialsinclude metal oxides and metal carbides. Examples of preferred ceramicmaterials include but are not limited to aluminum oxide, siliconcarbide, tungsten carbide and combinations thereof

In the case of a composite construction, there may be a metal bodyhaving a ceramic layer (e.g., in the form of a veneer or the like)covering all or a portion of the interface surfaces. If desired, thelayer can be provided in the form of a continuous surface or can beprovided in the form of one or more surface features projectingoutwardly a distance from the surface to contact the other plate plate.When the entire plate is not formed from a ceramic material, it isdesired that such layer have a thickness that is sufficient to provide adesired degree of low-friction service to provide a desired effectiveservice life without unnecessarily adding to the material costs. In anexample embodiment, it is desired that the ceramic layer or ceramicsurface feature have a thickness of at least 0.03 inches, and preferablyin the range of from about 0.03 to 0.1 inches.

Turning now to a description of a RAPP 30, and with reference to FIG. 1,the RAPP 30 can incorporate a set of ceramic port and valve plates 20and 10 each with a metal band 22 and 12. Instead of a set each with aband, one of the plates can include a band and the other may not. TheRAPP 30 comprises a stator assembly including a housing 32 having agenerally closed first end 34 at one axial end, and having an end block36 attached to an otherwise opposed open end 38 of the housing 32. Thevalve plate 10 is disposed within the housing 32 and is positionedadjacent an inside surface of the end block 54. The valve plate 10 doesnot rotate relative to the housing 32. A swash plate 40 is disposedwithin the housing 32 and positioned adjacent an inside surface of theclosed first end 34 of the housing 32. The swash plate 40 is astationary member that does not rotate relative to the housing 3 andprovides a smooth flat inclined surface that extends towards the portplate 20. A rotor assembly 42 is disposed within the housing andcomprises a cylindrical rotor-drum 44 that is interposed between theport plate 20 and the swash plate 40. The rotor-drum 44 is configured torotate within the housing 32 and comprises an array of axial cylinderbores 46, each fitted with an axial piston 48. Each axial piston 48comprises a ball-shaped end 50 in swivel engagement with a slider shoeor slipper 52 held against the inclined surface of swash plate 40. Theslipper 52 preferably, though not necessarily, comprises a ceramic bodyor at least a ceramic swash plate interface surface.

The slippers 52 are supported in a uniform array and held against swashplate 40 by a shoe pressure plate 54, which bears against the centralregion of rotor-drum 44 via a hemispherical swivel member 56. At theother end of rotor-drum, the attached valve plate 10 interfaces with theport plate 20 at a sliding interface to serve as a sliding valve controlsystem. The port plate 20 rotates with the rotor-drum 44 within thehousing 32.

The port plate 20 is configured having a number of openings therethrough, as shown in FIG. 7, that align with respective openings in thecylinder bores 46. The valve plate 10 also comprises openings, as shownin FIG. 5, that are in alignment with inlet and outlet ports (not shown)extending through the end block 36. As the rotor-drum 44 rotates withinthe housing 32, the port plate openings align with the valve openings tofacilitate fluid inlet and outlet in a manner corresponding to thepiston inlet and outlet strokes to provide the desired fluid transportby the RAPP 30.

Generally speaking, the internal components or parts of such RAPPs thatare subjected to frictional forces during pump operation include theinterface surfaces between the port plate 20 and the valve plate 10, theinterface surfaces between the swash plate 40 and the piston slippers52, and the interface between the piston ball-shaped end 50 and theslipper 52. When the RAPP is configured for use in oil hydraulictransport service, such interface surfaces are lubricated by the oilbeing transported, which operates to reduce the frictional forcesexisting at the metallic interfacing surfaces. However, when used forwater transport, the water can provide lubrication.

The use of ceramic materials is not limited to the valve and port plates10 and 20. Indeed, other parts can be formed of ceramic material for thepurpose of reducing and controlling unwanted frictional effects betweendynamically engaged surfaces. Depending on the particular internal part,the entire part can be formed from a ceramic material, or only a portionof the part can be formed from a ceramic material. For example, theslippers 52 and/or swash plate 40 can incorporate a ceramic material, asdescribed in U.S. Publ. Appl. No. 2013/0118346.

The banded ceramic valve and port plates, as well as the RAPPsincorporating the same, as disclosed herein may be embodied andpracticed in other specific forms without departing from the spirit andessential characteristics thereof. The present embodiments disclosed andillustrated herein are therefore to be considered in all respects asillustrative and not restrictive.

1. A rotary axial piston pump comprising: a housing; a swash plate, theswash plate having an inclined surface; a rotor assembly positionedadjacent the swash plate, the rotor assembly comprising a rotor-drumhaving at least one cylinder bore disposed therein, and having piston(s)disposed within the respective cylinder bore(s), the pistons having aball-shaped end extending from the cylinder bore(s); at least oneslipper interposed between the swash plate and the rotor-drum, theslipper(s) comprising socket joints for accommodating the pistonball-shaped end(s) therein, the slipper(s) having a swash plateinterface surface in contact with the swash plate inclined surface andoptionally formed from a ceramic material; a port plate positionedadjacent an end block disposed in the housing open end; and a valveplate interposed between the port plate and the rotor-drum; wherein theport and valve plates each have a ceramic surface at an interfacethereof; and wherein a reinforcing band is provided surrounding at leasta portion of one of the plates to hold the plate in compression.
 2. Therotary axial piston pump of claim 1, wherein the reinforcing band isprovided surrounding the valve plate.
 3. The rotary axial piston pump ofclaim 1, wherein the reinforcing band is provided surrounding the portplate.
 4. The rotary axial piston pump of claim 1, wherein thereinforcing band is provided surrounding the valve plate and a secondreinforcing band is provided surrounding the port plate to hold the portplate in compression.
 5. The rotary axial piston pump of claim 1,wherein the reinforcing band is metal.
 6. The rotary axial piston pumpof claim 1, wherein the reinforcing band is disposed about the outercircumference of the one of the plates.
 7. The rotary axial piston pumpof claim 1, wherein the one of the plates is ceramic, and thereinforcing band is disposed radially inward relative to an outercircumference of the plate.
 8. The rotary axial piston pump of claim 7,wherein the reinforcing band is provided with a recess.
 9. The rotaryaxial piston pump of claim 1, wherein the one of the plates is ceramic.10. The rotary axial piston pump of claim 1, wherein both plates areceramic and wherein the reinforcing band is provided surrounding thevalve plate and a second reinforcing band is provided surrounding theport plate to hold the port plate in compression.
 11. A set of valve andport plates, wherein each of the plates includes a ceramic interfacesurface for rotatably sliding engagement with the other plate, furthercomprising a reinforcing band radially surrounding one of the ceramicinterface surfaces to hold the surface in compression.
 12. The set ofvalve and port plates of claim 11, wherein the reinforcing band radiallysurrounds the ceramic interface surface of the valve plate.
 13. The setof valve and port plates of claim 11, wherein the reinforcing bandradially surrounds the ceramic interface surface of the port plate. 14.The set of valve and port plates of claim 11, wherein the reinforcingband radially surrounds the ceramic interface surface of the valve plateand a second reinforcing band radially surrounds the ceramic interfacesurface of the port plate to hold the surface in compression.
 15. Theset of valve and port plates of claim 11, wherein each of the plates isceramic and the reinforcing bands surround the outer circumference ofthe plates.
 16. The set of valve and port plates of claim 11, whereinthe plates are suitable for use in either a rotary axial piston pump orpressure exchanger.